Between 1884 and 1914, several hundred thousand male foreigners, chiefly Italian, entered unskilled occupations in France's "dual labor market." In French Lorraine, Italians formed an industrial labor underclass in mining and construction. This work analyzes the French response to this proletarian immigration: the construction of a citizen-foreigner border. The border was a social structure which functioned both to exclude alien workers from political and social rights and to subordinate foreigners in the labor market and the occupational hierarchy. It was formalized and reinforced by several French "immigrant policies." The Ministry of the Interior established special police controls over alien workers (1893) and used deportation as a tool to discourage Italian activism and upward social mobility. The Ministry of Commerce established quotas on the employment of foreign workers in the public sector (1899).The citizen-foreigner border has three major causes. First, French workers demanded primacy over aliens in the labor market and in the workplace. French workers clashed violently with Italians whenever the aliens transgressed social or spatial boundaries. French claims were supported by "labor protectionist" politicians with ties to Boulangist and other nationalist groups. Second, the French bourgeoisie demanded protection from the crime, disease and social unrest which they attributed to a foreign "dangerous class." Third, the French state provided security and primacy to citizens in order to expand its power and strengthen its legitimacy. France's "immigrant policies" were active and interventionist (if not always effective). They suggest that the Third Republic was not a "liberal state" which ignored immigration, but rather a "security state" which regulated the citizen-foreigner relationship. Its efforts prefigure more recent "immigration policy."The one exception to the exclusion of foreigners lies in the area of welfare. By treaty, Italian workers were included in French social insurance programs such as workmen's compensation (1898) and retirement pensions (1910). This suggests that humanitarian, international action may effectively challenge (or at least mitigate) the marginalization and subordination of foreigners.